The helicopter company owned by the son of the late Taoiseach Charles Haughey is on the latest list of tax defaulters published by the Revenue Commission.
Celtic Helicopters Limited, run by Ciaran Haughey, settled for just under €690,000 - half for under-declaring VAT and the other half in penalties.
The total amount recovered in the three months from April to the end of June was more than €146m.
It came to light as a result of the routine audit by the taxman.
Dublin City Council was also found to have under-declared tax, and made a settlement with Revenue for more than €500,000.
There were four settlements worth more than 1€m. The biggest was for €2.8m, by Padraig Drayne, a company director from Glenoory in Co Donegal.
Another large settlement was made by the developers of the Jervis Street Shopping Centre in Dublin, who are in voluntary liquidation, and settled for just over €1m.